diy mixer/patch bay

[flies]

hi everybody,

so i have purchased parts and stuff to make a (frac) rack of effects modules, and i thought what i'd do is have all the jacks and cables in the back and then route them to a patch bay, so i would be routing the ins and outs in one place. The main advantages of this plan, as i see it, are keeping away from modular spaghetti, all rack fx have their jacks in the back (afaik), and i can have more space for knobs on the front. I also wanted something like a splitter, so i could route one output a lot of other ins, and then a mixer to bring the threads together.

then i wondered then i had the idea that i could power the patch bay and add gains to all the channels, and use 1/4" jacks on the back, but banana cables on the front (user end). Using banana cables, i think i'd have to buffer all the inputs, and i might as well buffer the inputs with opamps with variable gain. That way, i can do all my splitting and mixing just by using the banana cables.

Right? will this idea work? i'm pretty sure i can split signals this way, but will it work to mix them as well?  Are there going to be problems using common ground (since banana cables have 1 lead)?

Or should i just build a matrix mixer instead?

[flies]

you can probably tell i'm new to the game, so please alert me to whatever misconceptions i'm working under! thanks!

[Paul Marossy]

I just built a patch bay a couple of weeks ago so I could either route my guitar to my effects unit/CD player/drum machine into my mixer so I can play along to CDs or my effects unit/drum machine into my digital multi-track recorder. Now, I just flip a switch and I can go from "practice" mode to record mode. I wish I would have built it a lot sooner! No more messin' around with cords and stuff.

BTW, I isolated signal grounds whereever I could to prevent ground loops. So far, no problems witg ground loops whatsoever. 

[flies]

BTW, I isolated signal grounds whereever I could to prevent ground loops. So far, no problems witg ground loops whatsoever. 

ok, so I didn't/don't really konw how to isolate signal grounds, so i looked here http://www.ecmweb.com/mag/electric_solving_instrumentation_ground/ and they say you use something called a "signal isolator" . this schem http://electronicdave.myhosting.net/pdf/genpurposemxr.PDF looks like it isolates the grounds.  here's a schem that doesn't http://www.forsselltech.com/summing_buss_schematics.htm .

for T1 in the first schem, will most transformers work? or do i need one specifically designed as a signal isolator?